BRI, I understand what you're saying, but what you just described goes to my (rhetorical) question earlier, which is why we don't drop the criminalization of the substance itself, and instead address the acts that result from the use. Using alcohol as an example, society has irrefutable proof that criminalizing possession does not deter use (see Prohibition). So, today we no longer fight that losing battle; rather than criminalizing the possession of alcohol, we criminalize behavior - behavior in which we say that the use of the substance doesn't justify the action. If you become so intoxicated that you are a risk to the public (either driving or committing an assault or a battery), we punish you for the driving or fighting. And we don't allow you to claim innocence due to intoxication. The drunk decided to drink, and any criminal activity that resulted therefrom is the reasonable consequences, and thus not a defense. Why not do that we all drugs?
Take meth as an example. We shouldn't care if someone has it or if they even use it - assuming that they don't harm others in the use. Rather, we should just punish for the acts that result. That would include cooking meth; it produces toxins that are extremely dangerous to the public. So, we criminalize that behavior. If you take meth and drive, we criminalize any damage you do.
I realize we already do that - what we don't do is recognize that crcriminalizinghe mere possession does no good per se. So, legalize the substances just like alcohol. Tax it. Regulate it. Punish anyone that, while under the influence, commits a criminal act.
Think about marijuana. In many respects, it's like alcohol. It slows reaction times, it impairs judgment. If you drive drunk, you are subject to criminal prosecution for endangering the public. But if you merely possess it, or use it in your own home, or drink responsibly in public, there's no crime. The same could be said about marijuana - the effects are the same, the impairment is the same, so treat it the same.
The same logic applies to any so-called illegal substance - possessing it alone, or using it "responsibly" (meaning, without endangering the public) should be fine.
Going back to your example of the guy that was under the influence and thinking strictly in terms of activity, does it really matter to the cop why the guy acted as he did? The crime is the same whether he was high, drunk, or just angry. The reason he acted as he did was irrelevant; the only relevant issue from a criminal conduct standpoint is that he was acting that way. Yes, he posed a greater risk to the public and to the police due to his drug use, but the same can be said of the guy who collects guns or weapons or body armor for years and goes out and has target practice - and then one day dons the body armor, loads the guns, and spays the public with gunfire. Up until he went nuts - regardless why he went nuts - society had no problem with him. It was only when he endangered the public that it became criminal. And like your example, his weapons and body armor posed a far greater risk to the public and police than if he'd just used his fists. So heighten the punishment of crimes committed under the infulence.
Nominate this as post of the year.